Step 2. Open?/Applications > Utilities > Terminal and then enter the following commands to creat Install macOS Sierra (disk2s1)

sudo su;
open /Volumes/linyongfeng\ HD/Library/Utilities/Install.macOS.10.12.6.MAS.dmg;
/Volumes/Install.macOS.10.12.6.MAS/Install\ macOS\ Sierra.app/Contents/Resources/createinstallmedia --volume /Volumes/USB --applicationpath /Volumes/Install.macOS.10.12.6.MAS/Install\ macOS\ Sierra.app --no interaction;

Step 3. After Done and then copy the necessary files into Install macOS Sierra (disk2s1)

cp /Volumes/linyongfeng\ HD/Library/Applications/ThinkPad\ x220\ macOS\ Sierra\ Utility\ and\ Kext\ pack.zip /Volumes/Install\ macOS\ Sierra;
cp -r /Volumes/linyongfeng\ HD/Library/Desktop\ Pictures /Volumes/Install\ macOS\ Sierra/;

cp -r /Volumes/linyongfeng\ HD/Library/Applications /Volumes/Install\ macOS\ Sierra/;
cp -r /Volumes/linyongfeng\ HD/Library/Utilities /Volumes/Install\ macOS\ Sierra/;

Step 4. Unzip the?ThinkPad X220 macOS Sierra?Utility and Kext Pack (ThinkPad x220 macOS Sierra Utility and Kext pack.zip) , Mount EFI on Install macOS Sierra (disk2s1) and copy the entire?EFI?folder?from the Utility and Kext Pack to the?EFI?partition of Install macOS Sierra (disk2s1), replacing the existing folder if present

mkdir /Volumes/EFI;
mount -t msdos /dev/disk2s0 /Volumes/EFI/;
unzip -o /Volumes/Install\ macOS\ Sierra/ThinkPad\ x220\ macOS\ Sierra\ Utility\ and\ Kext\ pack.zip -d /tmp;
cp -r /Volumes/Install\ macOS\ Sierra/ThinkPad\ x220\ macOS\ Sierra\ Utility\ and\ Kext\ pack/EFI /Volumes/EFI/;
rm /Volumes/EFI/EFI/.DS_Store; ls -a /Volumes/EFI/EFI/;
diskutil unmount /Volumes/EFI/;
rmdir /Volumes/EFI/;

ThinkPad-X220 macOS 10.12.6 Installation Document